Interstitial lung disease

Question 1

Briefly describe the pathology of ILD.

Answer 1

Disease that affect the lung parenchyma (functional part of lung i.e. for gas exchange e.g. alveoli) –> lung scarring/fibrosis.

Question 2

Briefly describe the pathophysiology of ILD

Answer 2

• Often idiopathic, however can be caused by smoking, pollutants, inhaled irritants
• Inflammatory response to the irritants and if that does not resolve –> progresses to remodelling of parenchyma to fibrosis
• Increased stiffness of lung tissue (reduced compliance)
• Hypoxaemia (gas exchange impairment due to damaged alveoli)
• abnormal collagen deposition around alveoli (scarred interstitium)

Question 3

What symptoms might someone with ILD have?

Answer 3

• SOB/dyspnoea - lung fibrosis reduces lung compliance (can’t take as deep breaths)
• dry cough - scar tissue in lungs
• substernal chest pain - severe coughing

Question 4

What signs might someone with ILD have?

Answer 4

• changed POB - decreased tidal volume + increased RR (decreased lung compliance due to fibrosis –> can’t take as deep breaths so compensates by breathing faster)
• reduced breath sounds - wheezing, fine crackles

Question 5

What might you hear if you auscultated this patient?

Answer 5

Reduced breath sounds - scarring of lungs decreases lung compliance and makes them more stuff, reduced efficiency of airflow

Fine crackles - snapping open of stiff, collapsed alveoli

Question 6

What features might you see on a CXR for someone with ILD?

Answer 6

• “Ground glass” opacities and honeycomb appearance due to dissolution of alveolar walls with formation of randomly distributed air spaces lined with fibrous tissues
• overall haze due to lung scarring

Question 7

What are the PFT findings for ILD?

Answer 7

Restrictive disorder

• decreased TLC - lung can’t fill up with as much air due to stiffness
• decreased FVC (fibrosis)
• FEV1 normal - no damage to the airways
• FEV1/FVC increased
• decreased DLCO (alveolar capillary membrane thickened)

Question 8

What impairments would someone with ILD have?

Answer 8

Gas movement impairment

• oxygen movement impairment (thickening of interstitium means oxygen can’t diffuse as efficiently into the bloodstream) –> diffusion problem means reduced oxygen (hypoxaemia, SOB)
• fibrosis of lungs makes lung stiffer and reduces ability for lungs to transport oxygen - reduced breathing efficiency (dry cough from scarring)